1. Field of the Invention
The present invention relates to an improved ophthalmologic apparatus comprising a trestle mounted on a base and laterally movable relatively to the base within a limited range and a measuring head unit mounted on the trestle and movable automatically relatively to the trestle in lateral direction with respect to a reference position within a predetermined range.
2. Description of the Related Art
An ophthalmologic apparatus such as a tonometer is known to comprise a trestle mounted on a base and laterally movable relatively to the base within a limited range and a measuring head unit mounted on the trestle and movable automatically relatively to the trestle in lateral direction with respect to a reference position within a predetermined range.
In such an apparatus as described above, rough alignment is carried out by moving the trestle longitudinally and laterally with respect to the base. When the eye to be inspected enters an auto alignment range, the measuring head portion is driven automatically in a predetermined range with respect to a reference position, thus making it possible to execute the measurement of the intra-ocular pressure automatically.
In the conventional ophthalmologic measuring instrument, however, the lateral relative travel range of the trestle is so limited that even when the trestle is moved laterally in full, the measuring head portion often fails to enter the auto alignment range and the measurement is impossible.
This situation occurs, for example, in the case where the face of the testee is not rightly directed toward the apparatus, In such a case, the testee is inconveniently instructed to direct his face rightly toward the apparatus. Also, the measurement may be impossible in the case where the width of the eye of the is too large.
A solution conceived to solve this problem is to enlarge the lateral relative travel range of the trestle with respect to the base. This configuration, if employed, would undesirably increase the space occupied by the ophthalmologic apparatus.
The present invention has been developed in view of this situation, and the object thereof is to provide an ophthalmologic apparatus in which even in the case where the lateral relative travel range of the trestle with respect to the base is limited, the measurement can be continued without enlarging the space occupied by the apparatus body and also without imposing an extra burden on the testee.
According to a first aspect of the invention, there is provided an ophthalmologic apparatus comprising a trestle mounted on a base and laterally movable relatively to the base with respect to a reference position within a limited range of relative movement, and a measuring head portion mounted on the trestle and automatically moved relatively to the trestle with respect to a reference position within a predetermined range, wherein when the trestle is moved in right or left direction and comes to be located at a movement limit position, the reference position of the measuring head portion with respect to the trestle is shifted in the direction in which the trestle moves.
According to a second aspect of the invention, there is provided an ophthalmologic apparatus comprising a trestle mounted on a base and laterally movable relatively to the base within a limited range of relative movement, a measuring head portion mounted on the trestle and automatically moved relatively to the trestle with respect to a reference position within a predetermined range in lateral direction, and a left/right decision switch for deciding which eye of right or left is to be measured, by laterally moving the trestle, wherein in the case where the left/right decision switch decides that the left eye is to be measured, the reference position of the measuring head portion with respect to the trestle is shifted leftward as viewed from the testee, while in the case where the left/right decision switch decides that the right eye is to be measured, the reference position of the measuring head portion with respect to the trestle is shifted rightward as viewed from the testee.
According to a third aspect of the invention, there is provided an ophthalmologic apparatus further comprising an announcing means for informing the testee that the reference position of the measuring head portion is shifted in the direction of movement of the trestle.
According to a fourth aspect of the invention, there is provided an ophthalmologic apparatus, wherein before the reference position of the measuring head portion is shifted relatively to the trestle in the direction of movement of the trestle, the head measuring unit is driven once in the direction away from the eye to be measured.
According to a fifth aspect of the invention, there is provided an ophthalmologic apparatus wherein in the case where the trestle is located at the movement limit position, the inspector is warned of the fact.
According to a sixth aspect of the invention, there is provided an ophthalmologic apparatus comprising a trestle mounted on a base and laterally movable relatively to the base within a limited range of relative movement, a measuring head portion mounted on the trestle and automatically moved relatively to the trestle within a predetermined lateral range with respect to a reference position, and a moving direction detection means for detecting the direction of movement of the trestle, wherein in the case where the moving direction detection means detects that the trestle moves leftward, the reference position of the measuring head portion with respect to the trestle is shifted leftward, while in the case where the movement direction detection means detects that the trestle moves rightward, the reference position of the measuring head portion with respect to the trestle is shifted rightward.